Spectroscopic, Structural Studies, Fluorescence and Optical Properties of Group VI Dinuclear Derivatives of N2O2 Schiff Base

Reaction of M (CO)6 (M = Cr, Mo and W) with 6, 6'(([1,1'biphenyl]4, 4'diylbis (azaneylylidene)) bis (methaneylylidene)) bis(2,4-dichlorophenol) H2L in THF were investigated. Under Sunlight irradiation, dinuclear carbonyl chromium complex [Cr2(CO)2L2] and two dinuclear oxo complexes [Mo2O4L2] and [W2O4L2] were isolated. In air, the corresponding reaction with Mo(CO)6 produced the dinuclear carbonyl oxo complex [Mo2O5(CO)L]. H2O. All complexes were characterized by elemental analysis, IR, mass and H NMR spectroscopy. Magnetic studies for [Mo2O4L2], [W2O4L2] and [Mo2O5(CO)L]. H2O complexes showed diamagnetic characteristics. TG-DTG study was done to track the thermal behavior of the complexes and the thermodynamic parameters were computed from the thermal data using Coats-Redfern and Horowitz–Metzger methods. The ultraviolet–vis spectra of the complexes in DMSO showed broad bands due to ligand-to-metal charge transfer. The fluorescence spectra of these complexes indicate the luminescence characteristics of the complexes. The values of optical band gap energy (Eg) of the synthesized complexes suggested that these compounds could be used as semiconductors.